Rare Candy counts as evolving a Basic Pokémon, letting a Stage 2 card go straight onto it from hand; the original Sandstorm wording also allowed a Stage 1. The Unleashed wording added that a Stage 2 in hand could be placed directly onto the Basic, and the Dark Explorers wording dropped Stage 1 and introduced the restriction against using it on the first turn or on a Pokémon put into play that same turn.
Rare Candy first appeared in Sandstorm in 2003 with art by Ryo Ueda, who illustrated it through several EX era sets. Noriko Hotta drew the Unleashed printing that introduced the Stage 2 clause, and Toyste Beach and Yoshinobu Saito illustrated later XY and Sword and Shield era prints. It has since picked up Secret Rare and Hyper rare treatments in Plasma Blast, Guardians Rising, and Scarlet and Violet, plus an Ultra Rare in the Mega Evolution era.
In Black and White, an erratum restricted Rare Candy so it can't evolve a Basic into a Stage 1, and can't be used on the first turn or on a newly played Basic; this new effect first appeared in print in Dark Explorers, matching the earlier effect of Pokémon Breeder. Rare Candy is named for the video game item that raises a Pokémon's level, and the Pokémon GO printing depicts the item as it appears in that game.
Sandstorm printing is Rare Candy's first appearance, illustrated by Ryo Ueda
Unleashed printing adds the Stage 2 direct-placement clause
Dark Explorers printing introduces the modern turn-restriction wording
Pokémon GO printing depicts the item as it appears in that game
Scarlet and Violet printing includes a Hyper rare treatment
Mega Evolution printing includes an Ultra Rare treatment
An erratum restricted it from evolving a Basic into a Stage 1 and from use on the first turn or a newly played Basic, matching Pokémon Breeder's older effect.
Its art depicts Rare Candy as it appears in the Pokémon GO mobile game, where it converts into Candy for a specific Pokémon.
Yes, a Hyper rare version appears in Scarlet and Violet.
From Sandstorm (2003) · 6 printings
Choose 1 of your Basic Pokémon in play. If you have a Stage 1 or Stage 2 card that evolves from that Pokémon in your hand, put that card on the Basic Pokémon. (This counts as evolving that Pokémon.)
From Unleashed (2010) · 1 printing
Choose 1 of your Basic Pokémon in play. If you have a Stage 1 or Stage 2 card that evolves from that Pokémon in your hand, put that card on the Basic Pokémon. (This counts as evolving that Pokémon.) If you choose a Stage 2 Pokémon in your hand, put that Pokémon on the Basic Pokémon instead of on a Stage 1 Pokémon.
From Dark Explorers (2012) · 4 printings
Choose 1 of your Basic Pokémon in play. If you have a Stage 2 card in your hand that evolves from that Pokémon, put that card on the Basic Pokémon. (This counts as evolving that Pokémon.) You can’t use this card during your first turn or on a Basic Pokémon that was put into play this turn.
From Sun & Moon (2017) · 3 printings
Choose 1 of your Basic Pokémon in play. If you have a Stage 2 card in your hand that evolves from that Pokémon, put that card onto the Basic Pokémon to evolve it. You can’t use this card during your first turn or on a Basic Pokémon that was put into play this turn.
From Sword & Shield (2020) · 8 printings
Choose 1 of your Basic Pokémon in play. If you have a Stage 2 card in your hand that evolves from that Pokémon, put that card onto the Basic Pokémon to evolve it, skipping the Stage 1. You can't use this card during your first turn or on a Basic Pokémon that was put into play this turn.

Rare Candy
Item
First printed in Sandstorm (2003)
Choose 1 of your Basic Pokémon in play. If you have a Stage 2 card in your hand that evolves from that Pokémon, put that card onto the Basic Pokémon to evolve it, skipping the Stage 1. You can't use this card during your first turn or on a Basic Pokémon that was put into play this turn.